West Pacific/2015/09W/Archive/4
Public advisory TROPICAL STORM CHAN-HOM PUBLIC ADVISORY NUMBER 4 WIKI-HURRICANES FORECASTING CENTER 6:00 AM JST WED JUL 01 2015 ...TROPICAL STORM CHAN-HOM SLIGHTLY STRONGER... SUMMARY OF 6:00 AM JST...21:00 UTC...INFORMATION ------------------------------------------------------------------- LOCATION...10.0N 160.0E CENTER POSITION CONFIDENCE: GOOD ABOUT 250 MI...405 KM NNE OF PALIKIR, MICRONESIA MAXIMUM SUSTAINED WINDS...40 KT...45 MPH...75 KM/H MINIMUM BAROMETRIC PRESSURE...1001 MB...29.56 INCHES PRESENT MOVEMENT...STATIONARY DISCUSSION AND 48-HOUR OUTLOOK --------------------------------------------- At 6:00 am JST, the center of Tropical Storm Chan-Hom was situated near 10.0N, 160.0E, or about 250 miles (405 kilometers) north-northeast of Palikir, Micronesia. Maximum sustained winds were 40 knots (45 mph, 75 km/h), with higher gusts. The minimum barometric pressure was 1001 millibars (hPa; 29.56 inHg), and the cyclone was stationary. Conditions are expected to become more conducive over the coming days as Chan-Hom continues to track west-northwest, which may allow it to strengthen with greater pace. NEXT ADVISORY ------------------- Next complete advisory at 12:00 pm JST. $$ Forecaster TAWX14 Discussion TROPICAL STORM CHAN-HOM DISCUSSION NUMBER 4 WIKI-HURRICANES FORECASTING CENTER 6:00 AM JST WED JUL 01 2015 Tropical Storm Chan-hom has changed little in organization this afternoon. The cyclone continues to produce a large and organized expanse of shower and thunderstorm activity, with cloud tops as cool as -100C observed at times. The low-level circulation, although better defined compared to this morning, continues to be exposed east of the convective mass. Recent satellite intensity estimates were a unanimous T2.5/35kt from both SAB and JTWC, with the recent value from UW-CIMSS ADT slightly lower at T2.2/32kt. However, given the longevity and intensity of the convective mass in association with Chan-hom, the initial intensity has been raised to 40kt. An ASCAT pass is expected to sample the core of the tropical storm around 23z and should provide us with more information on the strength and structure of the system. The upper-level environment is currently only marginally conducive for intensification, with 15 to 20 knots of southeasterly wind shear affecting the storm via a displaced anticyclone to the system's southeast. However, over the coming days, anticyclonic flow aloft is expected to balloon across Chan-hom. In addition, the upper-level setup should become even more favorable as a nearby upper-level low moves northward, opening up a substantial poleward outflow channel. Sea surface temperatures and ocean heat content values are expected to rise along the current projected path of the cyclone, favoring the potential for a rapid rate of intensification once an inner core is established. One factor that needs to be monitored is Chan-hom's interaction with nearby Invest 94W; such situations are not well understand in the world of meteorology at this time. The updated forecast closely follows the previous one in showing steady intensification over the next 72 hours, followed by a more rapid pace of development thereafter. A combination of conventional and microwave satellite imagery indicates that Chan-hom has slowed to a halt over the past few hours. However, the forecast philosophy remains the same. The cyclone is expected to progress steadily west or west-northwestward over the next 48 hours, steered by an expansive 594dm mid-level ridge to its north. Thereafter, global modelling indicates that Chan-hom will perform binary interaction with nearby Invest 94W, and both the GFS and ECMWF are in agreement that a west-southwest motion will occur for at least a brief period of time. By 96 hours, an upper-level trough is expected to dive southward into Japan and surrounding regions, acting to erode the western periphery of the mid-level ridge and turn Chan-hom toward the northwest. INIT 30/2100Z 10.0N 160.0E 40 KT 45 MPH 12H 01/0600Z 10.4N 159.1E 45 KT 50 MPH 24H 01/1800Z 10.9N 156.8E 50 KT 60 MPH 36H 02/0600Z 11.2N 153.7E 55 KT 65 MPH 48H 02/1800Z 11.5N 151.1E 60 KT 70 MPH 72H 03/1800Z 11.4N 148.2E 70 KT 80 MPH 96H 04/1800Z 13.9N 145.9E 90 KT 105 MPH 120H 05/1800Z 17.3N 142.4E 105 KT 120 MPH $$ Forecaster TAWX14